Rattlesnake noise

I received my OM-D about a month ago. It has the newest firmware (came installed from the factory). I have used it exclusively with the Pana/Leica 25mm f1.4 and have taken approximately 500 photos without incident. Today I heard the loud "rattlesnake" noise for the first time. It was clearly different from the normal IBIS sound and occurred even without depressing the shutter release (occurred when moving the camera across a bright window while inside). I turned the camera off and back on and have not heard the noise since My understanding is that the noise is caused by the aperture blades of the lens. My question is whether this damages the lens. Also, I have taken photos in similar lighting without incident. Have others seen this as an intermittent problem even with the new firmware? Thanks in advance for any information.